Python 标准库 -> StringIO模块 And cStringIO模块

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StringIO 模块的使用. 它实现了一个工作在内存的文件对象 (内存文件).

在大多需要标准文件对象的地方都可以使用它来替换.

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使用 StringIO 模块从内存文件读入内容

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import StringIO

MESSAGE = "abcdefg"

file = StringIO.StringIO(MESSAGE) # 将MESSAGE内容写入到内存中，并返回file类型到file变量



print file.read() # 读取内存文件内容

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使用 StringIO 模块向内存文件写入内容

StringIO 类实现了内建文件对象的所有方法, 此外还有 getvalue 方法用来返回它内部的字符串值

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file = StringIO.StringIO()

file.write("This man is no ordinary man. ") # 将内容写入到内存

file.write("This is Mr. F. G. Superman.") # 将内容写入到内存

print file.getvalue() # 输出file内存内容

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使用 StringIO 模块捕获输出

StringIO 可以用于重新定向 Python 解释器的输出

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import StringIO

import string, sys

stdout = sys.stdout

sys.stdout = file = StringIO.StringIO() # 将标准输出指向到内存



print """

According to Gbaya folktales, trickery and guile

are the best ways to defeat the python, king of

snakes, which was hatched from a dragon at the

world's start. -- National Geographic, May 1997

"""

sys.stdout = stdout

print string.upper(file.getvalue()) #从内存读出标准输出

ACCORDING TO GBAYA FOLKTALES, TRICKERY AND GUILE

ARE THE BEST WAYS TO DEFEAT THE PYTHON, KING OF

SNAKES, WHICH WAS HATCHED FROM A DRAGON AT THE

WORLD'S START. -- NATIONAL GEOGRAPHIC, MAY 1997

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cStringIO 模块

cStringIO 是一个可选的模块, 是 StringIO 的更快速实现. 它的工作方式和 StringIO 基本相同, 但是它不可以被继承

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使用 cStringIO 模块

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import cStringIO

MESSAGE = "That man is depriving a village somewhere of a computer scientist."

file = cStringIO.StringIO(MESSAGE)

print file.read()

That man is depriving a village somewhere of a computer scientist.

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后退至 StringIO

为了让你的代码尽可能快, 但同时保证兼容低版本的 Python ,你可以使用一个小技巧在 cStringIO 不可用时启用 StringIO 模块

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try:

import cStringIO

StringIO = cStringIO

except ImportError:

import StringIO

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